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High‐Temperature Crystal Structure and Chemical Bonding in Thermoelectric Germanium Selenide (GeSe)
Author(s) -
Sist Mattia,
Gatti Carlo,
Nørby Peter,
Cenedese Simone,
Kasai Hidetaka,
Kato Kenichi,
Iversen Bo B.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201700536
Subject(s) - materials science , orthorhombic crystal system , ionic bonding , van der waals force , crystallography , thermoelectric effect , chemical bond , lone pair , selenide , germanium , crystal structure , condensed matter physics , molecule , chemistry , silicon , thermodynamics , physics , ion , organic chemistry , selenium , metallurgy
The discovery of the ultra‐high thermoelectric figure of merit of 2.6 in SnSe has drawn attention to other lead‐free IV‐VI orthorhombic semiconductors. GeSe has been predicted to possess thermoelectric performances comparable to SnSe. Here, a complete structural study is reported of GeSe with temperature by means of high‐resolution synchrotron powder X‐ray diffraction. In the orthorhombic phase, the evolution of the bond distances with temperature is shown to deviate significantly with respect to SnSe. Analysis of the chemical bonding within the Quantum Theory of Atoms in Molecules shows that GeSe is ionic with van der Waals interlayer interactions. The signature of the N shell lone pair of Ge is also evident from both the electron density Laplacian and the ELF topologies.